A variety of growth factors, cytokines and differentiation factors that play a role in the physiology of normal and transformed cells have been identified and characterized during the last few years. The molecular mechanisms that are the basis for their biological activities are now beginning to be elucidated. Recent progress in developmental biology has revealed that these factors play key roles in inductive and instructive processes related to morphogenesis, proliferation, tissue differentiation and organogenesis. This conference will focus on the research progress in molecular mechanisms involved in expression and action of growth and differentiation factors in key development phenomena in vertebrates. The topics will include regulation of genes for growth and differentiation, in regulation of cell-cell and cell-matrix communication, in lineage-specific effects and in organogenesis. The specific systems that will be considered include hematopoiesis, neurogenesis, vasculogenesis and osteogenesis. The action of growth factors in developmental processes will be compared and contrasted with their roles in wound healing and malignancies.